Far out in the galaxy are Earth-sized exoplanets and super-Earths. And now, there's at least one mega-Earth.

Weighing 17 times as much as Earth, the newly discovered exoplanet, called Kepler-10c, is too big to be a super-Earth and too rocky to be a Jupiter-like gas giant. So Kepler-10c has acquired the title "mega-Earth," astronomers announced June 2 at the American Astronomical Society meeting in Boston.

Kepler-10c, which sits about 560 light-years from Earth in the constellation Draco, defies astronomers' ideas of how planets form, and other observations suggest that it isn't the only mega-Earth out there.